Medical practice shows that points in the skin of the human body exhibiting low electrical impedance are consonant with the location of pain sensation, and that providing electrical stimulation to those points can reduce the pain sensation temporarily. Moreover, if electrical stimulation is applied in a plurality of sessions over several days, the pain sensation can be reduced for long periods of time. Several devices and methods have been introduced for localizing the points exhibiting low impedance, and applying electrical stimulation thereto. One device is the Pointer Excel II Device, manufactured by TENS PLUS Industrial Company of Kwun Tong, Hong Kong, which consists of an apparatus comprising a probe for exploring the desired area of the body of the patient and searching for points exhibiting reduced impedance. When one such point is identified, the same apparatus is used to stimulate the point exhibiting low impedance using electrical currents. The electrode used for finding the points and providing the electrical stimulation consists of a metal rod with one end mechanically and electrically attached to the body of the apparatus and the other end having a round, ball-like termination that is pressed to the skin. It is well known that for this class of electrodes the amount of force applied to the skin during the low impedance detection phase affects the impedance measurement and consequently, for good results, the device must be operated by an individual skilled in finding points exhibiting low impedance. When used by an individual who is not sufficiently skilled, the device may not identify points exhibiting low impedance. Alternatively, a point that does not exhibit low impedance may be identified as exhibiting low impedance and electrical stimulation may be inappropriately applied without causing the desired effect.
An alternative device has been introduced, containing a plurality of sharp metal points or needles that are mounted on a flexible pad and applied to the skin with the sharp edges applying force on the skin and the other end mechanically supported by the flexible pad. An end of the pad is electrically connected to an electronic circuit that probes each needle, one at a time, determines if the point of the skin juxtaposed with the needle exhibits low impedance and, in the event that the point exhibits low impedance, applies electrical stimulation to that point. Unfortunately, because the needles are probed individually, the force applied to the skin by the plurality of needles may not be uniform and consequently the resulting impedance measurement is not reliable. Moreover, the sharp points have a reduced area for electrical connectivity with the skin, thereby complicating the supply of the relatively large voltage required for the electrical stimulation.
U.S. patent application Ser. No. 12/301,464, filed Nov. 19, 2008 to Naroditsky, the entire contents of which are incorporated herein by reference, describes a device wherein a plurality of electrodes in the form of metal rods are mechanically positioned in at least one array. The rods can move freely in a longitudinal direction such that when the device is juxtaposed with the skin the electrodes advance onto the skin thereby applying force depending solely on the weight of the electrode. If all the electrodes have the same weight, the force will be uniform. In this configuration, one end of the electrode applies force to the skin while the other end of the electrode is electrically connected to an electronics circuit that can probe each electrode and determine if the area of the skin juxtaposed with the particular electrode exhibits a low impedance, and in the event that the area of the skin exhibits low impedance, apply electrical stimulation to the area of skin via the electrode. Unfortunately, the electrodes measure the impedance of the outer layer of the skin which exhibits relatively high impedance. Thus, the high impedance of the outer layer of the skin may interfere with the measurement of the low impedance of the inner layers of the skin.
A technical paper titled “Mapping Acupuncture Points Using Multi-channel Device” by G. Kwok, M. Cohen and I. Cosic, describes a device wherein each electrode is a small diameter metallic pin which can penetrate the outer layer of the skin and thus measure the impedance of the inner layers of the skin. Disadvantageously, the penetration is performed in an uncontrolled manner which can cause inconsistencies in the impedance measurement. Additionally, due to their small size, a disposable device cannot be attached to the pins.